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Abstract:

A fluidic assembly for an air conditioning circuit comprises a first
feeding line for a high temperature fluid, a second feeding line
comprising a barrier material for a refrigerating fluid in the gaseous
state, and a casing defining a first inlet and a first outlet connected
to the second line; a chamber having an elongated shape and a minimum
upper cross dimension as compared to the first inlet and second outlet; a
second inlet and a second outlet connected to the first line; the fluidic
assembly comprising a radiating body adapted to be crossed by the high
temperature fluid and fluid-tightly connected to the casing between the
second inlet and the second outlet within the chamber for defining an
integrated silencer-exchanger assembly.

Claims:

1. A fluidic assembly for an air conditioning circuit, comprising a first
feeding line for a high temperature fluid, a second feeding line for a
refrigerating fluid in the gaseous state, and a casing defining a first
inlet and a first outlet connected to said second line; a chamber having
an elongated shape and a minimum upper cross dimension as compared to
said first inlet and second outlet; a second inlet and a second outlet
connected to said first line; said fluidic assembly comprising a
radiating body adapted to be crossed by the high temperature fluid and
fluid-tightly connected to said casing between said second inlet and
second outlet within said chamber for defining an integrated
silencer-exchanger assembly.

2. A fluidic assembly according to claim 1, characterized in that said
casing comprises a pair of shells.

3. A fluidic assembly according to claim 1, characterized in that said
casing has a side wall having substantially rectilinear generatrices and
a cross section having a larger dimension and a smaller dimension
different from said larger dimension.

4. A fluidic assembly according to claim 1, characterized in that said
radiating body comprises a tube having a longer length than said casing.

5. A fluidic assembly according to claim 1, characterized in that said
radiating body comprises radial ridges for increasing the heat exchange
surface.

6. A fluidic assembly according to claim 1, characterized in that it
comprises at least one partition adapted to intercept the flow of said
refrigerating fluid within said chamber.

7. A fluidic assembly according to claim 1, characterized in that said
second line comprises an inlet pipe and an outlet pipe connected to said
casing and in that said inlet and outlet pipes are misaligned.

8. A fluidic assembly according to claim 1, characterized in that said
first and second lines are connected to said casing by means of two
flanges.

9. A fluidic assembly according to claim 8, characterized in that at
least one of said flanges has a side opening such as to be mounted after
said first and second lines have been fluidically connected to said
casing.

10. A fluidic assembly according to claim 9, characterized in that it
comprises a front seal between said casing and an upsetting part of said
second line, and in that at least one of said flanges defines a recess
for accommodating at least said upsetting part so that said flange is
mounted substantially flat.

11. A fluidic assembly according to claim 1, characterized in that at
least said radiating body is glued to said casing.

12. A fluidic assembly according to claim 1, characterized in that at
least said radiating body is laser-welded to said casing.

13. An air conditioning system for a motor vehicle comprising a
compressor, an evaporator and a condenser, characterized in that it
comprises a fluidic assembly according to claim 1 for connecting said
compressor, condenser and compressor to one another.

14. A motor vehicle comprising an engine compartment and a fire-wall
delimiting said engine compartment, characterized in that it comprises an
air conditioning system according to claim 12, wherein said
exchanger-silencer assembly is applied to said fire-wall.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a fluidic assembly comprising a
heat exchanger for an air conditioning circuit of a motor vehicle.

BACKGROUND ART

[0002] An air conditioning circuit of a vehicle comprises a compressor, a
condenser, an expansion system, an evaporator and a fluidic assembly for
connecting the previously mentioned components to one another.

[0003] In particular, the evaporator is crossed by an air current which is
fed by specific air pipes into the passenger compartment and the
compressor may be arranged either in the front or in the back of the
engine compartment.

[0004] The compressor supplies work to take a fluid from a relatively low
temperature and pressure, e.g. 2° C. and 2 bars respectively, to a
higher pressure and temperature, e.g. 80° C. and 15 bars.

[0005] The fluid gives heat to the external environment in the condenser
and is directed towards the evaporator, an expansion valve being
interposed and which causes a pressure drop until the fluid evaporates in
the evaporator subtracting heat from the air flow which crosses it and
which is conveyed into the passenger compartment.

[0006] Downstream of the evaporator, the compressor must supply work to
the fluid equal to the enthalpy between suction and delivery. In order to
make the refrigerating cycle more efficient and reduce polluting
emissions, it is known to include a heat exchanger in which the fluid
exiting from the evaporator is heated by the fluid exiting from the
condenser. Thereby, the fluid aspirated by the compressor has a higher
pressure and temperature, and both the enthalpy and consequently the work
of the compressor decrease.

[0007] In particular, heat exchangers are known in which the low pressure
fluid pipe is concentric to the high pressure fluid pipe. Such an
exchanger comprises an extruded aluminum tube.

[0008] The known exchanger requires specifically designed fittings to
connect an extruded tube defining pipes which are concentric with the
other components of the circuit. This, in combination with the tube being
obtained by extrusion, implies relatively high manufacturing costs of the
heat exchanger.

[0009] Furthermore, the concentric pipes easily fit an air conditioning
circuit in which the compressor is mounted in frontal position in the
engine compartment. Indeed, in this case, for needs of layout, the high
and low pressure tubes are arranged side-by-side.

[0010] However, the compressor may also be mounted in a rear part of the
engine and, in this case, the high and low pressure pipes are not
arranged side-by-side, so that the known exchanger either cannot be used
or needs additional connection tubing.

[0011] In the air conditioning circuits, it is further known to use a
reactive capacitance silencer defined by an expansion chamber. The
expansion chamber is a capacity normally inserted on the low pressure
line upstream of the compressor suction to adjust the gas flow entering
the compressor. The noise of the latter is so reduced.

[0012] When the compressor is arranged behind the motor, the silencer also
requires dedicated connections and brings about layout problems.

[0013] A known exchanger may have labyrinths therein, which are defined by
soundproofing and/or dissipating fillers, for example.

DISCLOSURE OF INVENTION

[0014] It is the object of the present invention to provide a fluidic
assembly for an air conditioning circuit provided with a heat exchanger
which is free from the above-specified drawbacks.

[0015] The object of the present invention is achieved by a fluidic
assembly according to claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] For a better understanding of the present invention, it will now be
further described with reference to the accompanying figures, in
particular:

[0017]FIG. 1 is a perspective view of a fluidic assembly according to the
present invention;

[0021]FIG. 5 is a perspective view of a fluidic assembly according to a
further embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] In FIG. 1, numeral 1 shows as a whole a fluidic assembly for an air
conditioning system of a motor vehicle, comprising a high pressure line 2
for feeding a refrigerating fluid between the delivery of a compressor
and an expansion valve, and a low pressure line 3 to feed a refrigerating
fluid from the expansion valve to the compressor suction.

[0023] In particular, the high pressure line 2 comprises metal and rubber
pipes mounted in series, a fitting 4 adapted to be connected to the
delivery of a compressor, a fitting 5 connected to the inlet of a
condenser and a tube 6' between the fittings 4 and 5. Furthermore, the
high pressure line 2 comprises a pipe 6 for connecting the condenser to
an expansion valve (not shown). The pipe 6 comprises a fitting 7 adapted
to be connected to the outlet of the condenser and a fitting 8 adapted to
be connected to the expansion valve.

[0024] The low pressure line 3 comprises a pipe 9 having a fitting 10
adapted to be connected to the outlet of an evaporator (not shown) and a
fitting 11 adapted to be connected to an inlet of the compressor.

[0025] The pipes of lines 2, 3 comprise at least one layer of a barrier
material for preventing the permeation of the normally very volatile
refrigerating fluid. For example, the material may be aluminum or a
polyamide 6.10. In the case of an carbon dioxide system, the tubing is
made of steel.

[0026] According to the present invention, the fluidic assembly 1
comprises an exchanger-silencer assembly 12 mounted on the fire-wall 13
(only outlined in FIG. 1) and arranged close to the fittings 8 and 10.

[0027] In particular, the exchanger-silencer assembly 12 allows both to
decrease the pulses of the refrigerating fluid in the gaseous state,
which cause undesired noises, and to heat the refrigerating fluid in the
gaseous state itself to decrease the enthalpy between the compressor
suction and delivery.

[0028] FIGS. 2 and 3 show the exchanger-silencer assembly 12 which
comprises first and second half-shells 14, 15 joined by means of a
gas-tight welding along a respective butt edge, e.g. TIG welding, to form
a casing 16, a first connection flange 17 firmly connected, e.g. by means
of a pair of screws 18, to the half-shell 14, and a second connection
flange 19 firmly connected, e.g. by means of a pair of screws 20, to the
half-shell 15.

[0029] In particular, each half-shell 14, 15 is cup-shaped having a flat
face 21, and the flanges 17, 19 are also flat and applied to the
respective faces 21. The half-shells 14, 15 are preferably identical and
made by impact extrusion processing.

[0031] The casing 16 defines an inlet 22 and an outlet 23 for the high
pressure line 2, and an inlet 24 and an outlet 25 for the low pressure
line 3.

[0032] The exchanger-silencer assembly 12 comprises a radiating body 26
connected between the inlet 22 and the outlet 23. The inlet 22 and the
outlet 23 preferably define a flare and the radiating body 26 comprises a
metal tube 27, the end edges of which are widened and fluid-tightly
welded onto respective flares.

[0033] According to an embodiment, the high pressure line 2 is fluidically
connected to the radiating body 26 by means of an inlet portion 28 and an
outlet portion 28'. The inlet and outlet portions 28, 28' are preferably
identical and only the inlet portion will be described hereinafter for
conciseness.

[0034] In particular, the inlet portion 28 defines a seat 29 for a sealing
ring (not shown), and a bead 30 which is clamped against the welded edge
of the tube 27 by the flange 19 by means of screws 20. The sealing ring
prevents leakage of refrigerating fluid from between the tube 27 and the
high pressure line 2, and the weldings between the tube 28 and the casing
16 ensure that the refrigerating fluid of the high pressure line 2 cannot
escape outwards.

[0035] The low pressure line 3 is connected to the casing 16 by means of
an inlet portion 32 and an outlet portion 33. The inlet and outlet
portions 32, 33' are preferably identical and only the inlet portion will
be described hereinafter for conciseness.

[0036] In particular, the inlet portion 32 defines a bead 34 which rests
on a spring washer 35 substantially parallel to the flat face 21 and
defining a front seal for the refrigerating fluid. The bead 34 and the
spring washer 35 are pressed by the flange 17 and the screws 18 so as to
form a rigid fluid-tight connection and to avoid the refrigerating fluid
in the gaseous state from being dispersed into the external environment.

[0037] In a preferred embodiment, the flanges 17, 19 define respective
diametrical grooves 38 (one of which is illustrated in FIG. 3) radially
open so as to be mountable after the exchanger-silencer assembly 12 has
been connected to the lines 2, 3.

[0038] The flanges 17, 19 preferably consist of a flat plate for shearing,
the plate having recesses for correctly accommodating the upsetting parts
of the tubing. In particular, the beads 30 have an axial dimension
different from that of the beads 34 because they are made on tubes of
different thickness. The presence of recesses thus allows to recover such
a difference of size and keep the flange 17, 19 substantially flat to
ensure the correct operation of the spring washers 35. Thereby, each
flange 17, 19 simultaneously connects two respective portions 28', 32 and
28, 33.

[0039] According to a preferred embodiment of the present invention, the
radiating body 26 comprises a plurality of radial ridges 36
diagrammatically shown in FIG. 4. The radial ridges 36 increase the ,heat
exchanging surface between the tube 27 and the refrigerating fluid within
the chamber 31. The radial ridges 36 preferably comprise metal wires
radially arranged and glued onto the tube 27.

[0040] The exchanger-silencer 12 is mounted as follows.

[0041] The radiating body 26 is inserted into the half-shells 14, 15 and
the latter are welded together.

[0042] The end edges of the tube 27 are then widened to adhere to the
respective flares of inlet 22 and outlet 23, and the edges are also
welded.

[0043] Finally, the exchanger-silencer assembly 12 is mounted to the high
and low pressure lines 2, 3 as previously described by using the flanges
17, 19.

[0044] The advantages of the fluidic assembly made according to the
present invention are apparent from the description provided with
reference to the accompanying figures.

[0045] The low pressure line 3 defines the chamber 31 within which the
refrigerating fluid in the gaseous state expands and is heated by the
means of the radiating body 26. The chamber 31 further defines a capacity
which damps the pressure pulses. In particular, such an effect is
increased by the chamber 31 accommodating the radiating element 26. This
indeed causes a labyrinth effect along the refrigerating fluid path.
Therefore, an air conditioning circuit provided with the
exchanger-silencer assembly 12 does not require the presence of a further
silencer and integrates two functions in a single component.

[0046] In particular, to define an accumulation volume, the chamber 31 has
a minimum cross dimension larger than the diameter of the inlet and/or
outlet portion 32, 33.

[0047] The high pressure line 2 may be connected to the exchanger-silencer
assembly 12 by means of connections normally used in air conditioning
circuits, and the costs are therefore reduced and the reliability already
proven.

[0048] The exchanger-silencer assembly 12 may be mounted on systems having
a front compressor and on those having a rear compressor (as that shown
in FIG. 1).

[0049] It is finally apparent that changes and variations may be made to
the present invention without departing from the scope of protection
defined by the appended claims.

[0050] For example, in addition to a circular cross section, the casing 16
may also have an elliptical section to save space when it is mounted on
the fire-wall.

[0051] The two half-shells 14, 15 may be mounted on a through tube, on
which the radial ridges 36 have been applied in advance. The shells 14,
15 may surround the ridges 36 and then be welded to each other and to the
through tube at the ports 22, 23. Thereby, the connections made by the
inlet and outlet portions 28, 28' may be avoided, the costs may be
further reduced and an optimal sealing may be ensured.

[0052] In order to increase the heat exchange efficiency, the shells 14,
15 may define partitions which extend the flow of the refrigerating
liquid in the gaseous state flowing from inlet 24 to outlet 25, such as
for example partition 40 in FIG. 4.

[0053] Furthermore, the inlet and outlet portions 32, 33 may be coaxial,
as shown in FIG. 4, or misaligned. Even in the latter case, the path of
the refrigerating fluid within the chamber 31 is extended. Preferably,
the portions 32, 33 are on opposite parts of a plane crossing an axis A
of the tube 27.

[0054] The flanges 17,19 may be made by shearing or die-casting.

[0055] The exchanger-silencer assembly 12 may also be mounted in other
positions, i.e. on a side member.

[0056] The exchanger-silencer assembly 12 may be arranged either between
the tube 6' comprised between the fittings 4 and 5, i.e. between the
compressor delivery and the condenser inlet, and the pipe 9, or be
connected to another high temperature fluid source, e.g. the cooling
water.

[0057] Furthermore, the half-shells 14, 15 and/or the tube 27 and/or the
radial ridges 36 may be glued by means of a structural sealing adhesive
instead of being welded. Thereby, an excessive heat supply to the
components during the manufacturing process may be avoided and the
sealing needed to prevent leakages of refrigerating fluid is kept in all
cases.

[0058]FIG. 5 shows a second fluidic assembly 50 for an air conditioning
system in which the compressor is mounted in front of the engine. Such a
figure shows how the exchanger-silencer assembly 12 may be mounted
instead of the silencer normally used in this type of systems and
indicated by reference number 51.

[0059] The fluidic assembly 50 will be described hereinafter so that the
reference numbers used in the previous description indicate like elements
or elements corresponding to those previously described.

[0060] In particular, the fluidic assembly 50 comprises the high pressure
line 2, in which fitting 4 is connected to the compressor delivery and
fitting 8 is connected to the expansion valve inlet, and the low pressure
line 3 in which fitting 10 is connected to the outlet of the evaporator
and fitting 11 is connected to the compressor suction.

[0061] In particular, the high pressure line 2 comprises the pipe 6
connected between the condenser outlet and the expansion valve. The low
pressure line 3 comprises the pipe 9 connected between the evaporator and
the compressor to feed refrigerating liquid in the gaseous state at low
pressure and low temperature.

[0062] According to the configuration shown in FIG. 5, the pipes 6 and 9
are arranged side-by-side and the exchanger-silencer assembly 12 is
mounted over the length in which the pipes 6 and 9 are close to each
other.

[0063] Furthermore, instead of gluing, laser welding technology may be
used to made the exchanger 1, as mentioned above. Thereby, the heat
supply is localized in a particularly precise manner with respect to
other welding techniques so as to prevent high deformations and
distortions and to preserve the crystalline structure of the zones
adjacent to the welding. For example, laser welding may be used for
joining at least one of the pipes 6, 9 to the casing 16. Furthermore, the
casing 16 may also be made in more than two parts and at least two of
these parts may be welded together by means of laser technology.